Precise control distribution of airplane fuel stores



March 1, 1960 R. A. MUMA EI'AL 2, 2

PRECISE CONTROL DISTRIBUTION OF AIRPLANE FUEL STORES 2 Sheets-Sheet 1 vFiled May 8, 1956 March 1, 1960 R. A. MUMA ETAL PRECISE CONTROLDISTRIBUTION OF AIRPLANE FUEL STORES Flled May 8, 1956 2 Sheets-Sheet 2GT OENEY modified and 1 With n tt fi :t ue :intcnt and .scope 30f theinvention as United States Patent .PREQ SE CONTROL DI TRIBUT OFAIRlPLANE FUELSTORES Richard A. Muma :and John Lee Markley, Wichita,Kano, :assignors to 'Beech Aircraft Corporation, .Wighita, .Kansx, acorporation of Delaware Application May 8, 1956, sen in 533,599

10 Claims. 01. 137-263 -scribed bydesign of the aircraft.

With growth in the loads of fuel to be carried, the

matter of C.G. control has become progressively more important andvarious systems for sequencing use of fuel from different tank cellshave been developed. These, for the most part, have been complicated,expensive and hardly sufficiently accurate or reliable forpracticalsafety requirements.

Accordingly, objects of the present invention are to provide simple,practical and reliable low cost fuel distribution accuratelto -the C-G.limits of the airplane desi readilymnderstood :by users, made up so faras possi-bletof readily replaceable standard parts and units andcomprising a system which may be readily installed in airframes now inuse and presently under design and development; further, -:to make thissystem fail safe throughout, :protecting the center of gravity controland enabling use of the main fuel supply after shutdown of the automaticcontrol andtto pennit -dumpingwhile main- :tainingscenteriof gravitycontrol.

The z-foregoing and other important objects attained by thelinvcntionand the movelfeatures of constructiomcom- 'binationtand relation ofparts through twhichthe purposes .ofitheliuvention are accomplished are-set forth and will iappearmorefullydn vthe courseIofthe followingspecificatioh.

The drawing accompanying and forming part of the.spccjficationlisillustrative of present embodiments of the inyention{bl-1t, 1218 will become apparent, structure may be changed 18.8 regardsimmediate illustration,

.. en efin dand c im EEig. 1 n thetdrawingiisn brokenlplan vview of anair- .ng a lon i u ina tcontroltembodiment of the .inyent on appliedthereto in the form of wing tip dividedjncells 1, 1231M 32withthecriticallylocated 1s and 1; a te nate y seque c d "t upp y t a loeatee tersells t. 1s; i -a side v c o QQF/Q th due s cr z uuit wit th timerndl ansfe pump fo r ng om the and cel s n t e dii t h c te e ind ca ediagrammatically.

.Eis-Ai an e lar d a d par yz ect ned d e ation th wins t p-tan un ra ts wn mat in detail.

4 is afrontview ofan airplaneequipped forlateral c n rolas winsdiagrammaticallvs tank 11 4 43 44 and 5 r spec ly sequ n ed: to thenun-c t ente tc ll .3-

;E s. .fli a iagram il ust a in n e tisn nd p atimb the el ment cmb edasinFig. 3.

In the longitudinal control forrn of th li yentionshown inliissza fi.thct wsi ar ue c cre ar c r by .1 2 th nks 7 and 8 d stoth aurilia ysnmam.taaksl ntc arde aitplanc- I l 2,926,688 Patented Mar. 1, 1960 ICC?This fuel supply system in the carrier airplane may be of conventionaldesign with auxiliary and main tanks connected to left and right-handengine pumps and tanks of the opposite pairs cross connected.

The left and right-hand stores units may be connected with the left andright fuel supply lines of the carrier by break away joints as indicatedat 9, Fig. 3.

in the illustration the stores tanks are broken up or divided into thethree longitudinally alined cells 1, 2 and 3 with the intermediate orcenter cells 2 located in non-critical and the end cells land 3 in thecritical positions.

These end cells may be of equal capacity, say, 21.5 gallons and thecenter non-critical cell, designed to be drawn from, of greatercapacity, say, twenty-seven gallons.

Fig. 3 shows the fuel transfer line 10 extending from the center cell 2-to the pull-away fitting at the end of the carrier fuel supply line.

A booster pump 11 in the center tank cell provides the flow from thenon-critical tank cell through the transfer line to the engine supplysystem. This pump, in the example under consideration, might have acapacity of fifty gallons per hour to feed one engine, to cross feedbot-h engines or to feed one engine plus transfer of fuel to refill anauxiliary tank.

Fuel quantity in the center cell is maintained by sequence pumping fromthe end cells and at much higher rate, for instance in the examplegiven, at one hundred and fifty gallons per hour.

For accomplishing these results, the end cells are manifolded by aconnection1-2 having inlets 13, 14 at opposite ends to the cells 1 and 3and a greater volume positive displacement transfer pump 15 is connectedat its inlet side into the manifold at 16 and at its discharge side intothemiddle ccll2 at 17.

Dump valves for the end cells are connected into the manifold at 18, 19and to provide immediate full flow to these valves the opposite ends ofthe manifold are shown as enlarged to the dump valves, as indicated at20, 21. The center cell is shown as having a dump valve 22 connecteddirectly thereto.

Suitable controls are provided usually by which the center cell can bedumped separately for ballast control or all three cells be dumpedsimultaneously as in case of an emergency.

Center of gravity control is retained during dumping by hydraulicbalance of the dump manifolds, as shown and described.

Selection of the two end cells is effected in the illustration bynormally closed C.G. control solenoid valves 23, 24 in theinterconnecting manifold at opposite sides of the transfer pump inlet16. These selecting valves are in turn controlled by a C.G. controlfloat switch 25 located in the center cell. This may be a two-positionswitch connected as indicated at 26, 36, with the transfer pump 15 andwith-a roto-timer 27 The latter is shown as connected at 28, 29 with thetwo selecting or sequencing valves 23, 24.

Theseconnections from the float controlled switch are arranged to startthe transfer pump 15 and the roto tinier 27 when the float drops to itslow positionand to stop th trans rl rn and time whe th flo rises to itsp e hi h lc c positi n- Thegoto-timer when started selectfs which valve,either 23 c 24, is to open ,and hence the end cell to restore or to helprestore the level oftliquid in the center cell.

A specia .QG- contr floa pe ateds w it h 30 is shown located in thecenter cell conneptedat 3,1 to turn off the transfer pump 15 androto-tiiner 27 and close the sequencing valves 23, 2,4 whenfuelisexhausted from the end cells V and the, liquidjn the center cell drops tthi cw n w heate floatsw tshconnected to protect the booster pump 11from a dry run.

Float opening valves 33, 34 are shown connecting the end cells with themanifold to assure complete draining of these cells in flight attitudesother than level.

A pressure switch 35 is indicated in the intake to the transfer pump,connected to turn off this pump and the roto-timer in case ofmalfunctioning of the sequencing valves 23, 24.

The roto-timer is constructed and connected to prevent closure of thetransfer pump circuit in case of malfunctioning of any type in thetimer. These features protect the center of gravity control.

After circuit shut-down of the automatic system, the contents of thecenter cell, 27 gallons in the illustration, are available for use.

Fig. 5 is a simplified diagram showing electrical connections by whichbooster pump 11 is started by float switch 25 in the center cell toeffect transfer from one of the end cells in accordance with which oneof the sequencing valves 23, 24 is selected by the timer 27 which, withtransfer pump is connected to be started when the float switch lowers inthe center cell.

In the lateral control embodiment of the invention illustrated in Fig.4, tank cells 41, 42, 44, 45 respectively are disposed in pairs atopposite sides of the center fuselage located center tank 43. The latteris in non-critical position usually at higher level than the side cellsas shown.

The outer cells 41 and 45 respectively are shown connected bymanifolding sections 12a containing sequencing valves 23a connected withthe timer at 28a, and the inner cells 42 and 44 respectively are shownsimilarly connected by manifolding sections 12b directly connected tothe transfer pump and containing sequencing valves 24a having controlconnections 29a with the timer.

In this manner liquid is alternately drawn from the outer and the innertank cells to replenish that removed from the center cell.

Since the action of replenishing the center collecting tank from thesupply tanks at opposite sides of the same is the same as in the firstdescribed form of the invention substantially the same wiringconnections may be emploved as indicated in Fig. 5.

By means of differently cut earns the roto-timer may be made to causethe transfer pump to Withdraw equal or unequal amounts of fuel from thedifferent feed tanks and the timing may be such as to keep the transferpump in action, taking relatively small quantities of fuel from thedifferent tanks in a way to equalize and maintain practically constantC6.

The cells may be simply partitioned portions of a single tank unit or beentirely separate tanks and as has been shown these feed sources may bedisposed longitudinally or laterally of a main supply body so termsemploved here are to be thus understood.

The sequence of pumping disclosed assures equal usage of fuel, in thepresent example, within approximately onehalf gallon limit, and hencefor all practical purposes serves to prevent composite fuel center ofgravity shift.

The timer selects the proper end or side feed cell for correct sequenceand starts the transfer pump and keeps it running long enough towithdraw a volume of liquid which will balance or compensate for thatpreviously removed from an opposing cell or such as will be balanced orcompensated bythe following sequencing operation. If the CG. controlfloat switch in the supply cell shuts off the timer before completion ofa pumping cycle, the timer will automatically pick up and complete thatcycle and then carry on from there on the next energization by thecontrol float.

The system is fail safe" throughout. A solenoid valve and a check valvein the main fuel pressure line of the carrier airplane prevent fuel flowfrom the carrier back to the stores unit. The pressure switch 35 in theintake aeaaess a to the transfer pump turns off the transfer pump andrototimer in case of malfunctioning of sequencing valves 23 and 24. Therotor-timer 27, is designed to prevent closing of the transfer pumpcircuit in case of any malfunctioning of the timer, all these featuresprotecting the center of gravity control. Float operated shut-downswitch 30 shuts down the CG. control system, should transfer pump 15become inoperative, so as to prevent continued sequencing of thesolenoid transfer valves and possible transfer of fuel through transferpump by-pass due to static head. When the automatic part of the systemshuts down, as it does if anything goes wrong, leaving C.G. properlycontrolled, the main supply in the center cell continues'ready for use.

The controlled method of operation is accurate and reliable. The partsare relatively few and generally standard units which may be readilyassembled and replaced if need be.

Cost of the complete system is reasonable, for results accomplished.Operation is readily understood and necessary controls and indicatorsmay be few and simple in character.

While generally a positive displacement pump may be used as a transferpump 15, it is contemplated that these transfer operations may beeffected by tank cell pressun'zing.

What is claimed is:

1. In combination with an airplane, precise control distributionofairplane fuel stores comprising a center fuel supply cell located innon-critical position with respect to the center of gravity of theairplane and supplying cells in more critical center of gravitypositions at opposite sides of said supply cell, a manifold connectingsaid side cells, a transfer pump connected at inlet side with saidmanifold and at discharge side with said center cell, sequencing valvesin said manifold at opposite sides of said pump inlet, a timer connectedto alternately open said sequencing valves and to hold said transferpump energized for predetermined intervals of time whereby to feed saidcenter cell with predetermined quantities of fuel taken alternately fromthe respective side cells and a float actuated switch at said centercell connected to start said timer and transfer pump when fuel in thecenter cell falls below a predetermined level and to stop said timer andtransfer pump when fuel taken from said side cells restores fuel in saidcenter supply cell to the original predetermined level.

2. In combination with an airplane, precise control distribution ofairplane, fuel stores comprising a center fuel supply cell located innon-critical position with respect to the center of gravity of theairplane and supplying cells in more critical center of gravitypositions at opposite sides of said supply cell, a manifold connectingsaid side cells, a transfer pump connected at inlet side with saidmanifold and at discharge side with said center cell, sequencing valvesin said manifold at opposite sides of said pump inlet, a timer connectedto alternately open said sequencing valves and to hold said transferpump energized for predetermined intervals of time whereby to feed saidcenter cell with predetermined quantities of fuel taken alternately fromthe respective side cells, a float actuated switch at said center cellconnected to start said timer and transfer pump when fuel in the centercell falls below a predetermined level and to stop said timer andtransfer pump when fuel taken from said side cells restores fuel in saidcenter supply cell to the original predetermined level and a shutdownfloat switch operating at a lower level in said center supply cell andconnected to cause closure of said sequencing valves and stoppage ofboth the timer and transfer pump when fuel in the center supply tankdrops to the lower level of said shutdown float switch.

3. In combination with an airplane, precise control distribution ofairplane fuel stores comprising a center fuel supply cell located innon-critical position with spect to the center of gravity of theairplane andzsupplying cells in more critical center of gravitypositions at opposite sides of said supply cell, a manifold connectingsaid side cells, a transfer pumpconnected at inlet :side with saidmanifold and at discharge side with said center cell, sequencing valvesin-said manifold at opposite sides of said pump inlet, a timerconnectedto alternate'lyopen said sequencing valves and to holdoaidtransferupump energized for predetermined intervals of time whereby tofeed said center cell with predetermined quantities of fuel takenalternately from the respective side cells, a float actuated switch atsaid center cell connected to start said timer and transfer pump whenfuel in the center cell falls below a predetermined level and to stopsaid timer and transfer pump when fuel taken from said side cellsrestores fuel in said center supply cell to the original predeterminedlevel, a boost pump for removing fuel from the center cell and a lowlevel float switch at said center supply cell connected to prevent saidboost pump from a dry run.

4. In combination with an airplane, precise control distribution ofairplane fuel stores comprising a center fuel supply cell located innon-critical position with re spect to the center of gravity of theairplane and supplying cells in more critical center of gravitypositions at opposite sides of said supplycell, a manifold connectingsaid side cells, a transfer pump connected at inlet side with saidmanifold and at discharge side with said center cell, sequencing valvesin said manifold at opposite sides of said pump inlet, a timer connectedto alternately open said sequencing valves and to hold said transferpump energized for predetermined intervals of time whereby to feed saidcenter cell with predetermined quantities of fuel taken alternately fromthe respective side cells, a float actuated switch at said center cellconnected to start said timer and transfer pump when fuel in the centercell falls below a predetermined level and to stop said timer andtransfer pump when fuel taken from said side cells restores fuel in saidcenter supply cell to the original predetermined level and float valvesin the side cells at entrances to said manifold.

5. In combination with an airplane, precise control distribution ofairplane fuel stores comprising a center fuel supply cell located innon-critical position with respect to the center of gravity of theairplane and supplying cells in more critical center of gravitypositions at opposite sides of said supply cell, a manifold connectingsaid side cells, a transfer pump connected at inlet side with saidmanifold and at discharge side with said center cell, sequencing valvesin said manifold at opposite sides of said pump inlet, a timer connectedto alternately open said sequencing valves and to hold said transferpump energized for predetermined intervals of time whereby to feed saidcenter cell with predetermined quantities of fuel taken alternately fromthe respective side cells, a float actuated switch at said center cellconnected to start said timer and transfer pump when fuel in the centercell falls below a predetermined level and to stop said timer andtransfer pump when fuel taken from said side cells restores fuel insaid'center supply cell to the original predetermined level, the endportions of the manifold which are connected with the side cells beingenlarged and dump valves in said enlarged end portions of the manifold.

6. In combination with an airplane, precise control distribution ofairplane fuel stores comprising a center fuel supply cell located innon-critical position with respect to the center of gravity of theairplane and supplying cells in more critical center of gravitypositions at opposite sides of said supply cell, a manifold connectingsaid side cells, a transfer pump connected at inlet side with saidmanifold and at discharge side with said center cell, sequencing valvesin said manifold at opposite sides of said pump inlet, a timer connectedto alternately open said sequencing valves and to hold said transferpump energized :for predetermined f time" whereby to ,feed :said centercell. with predetermined quantities of fuel taken alternately from therespective side cells, a float actuated switch at said center cellconnected to start said timer and transfer pump when fuel in the centercell falls below a predetermined level. and to stop said timer andtransfer pump when fuel taken from said side cells restores fuel in saidcenter supply cell to the original predetermined level, dump valves inthe end portions of said manifold and the center cell having a separateindependently operable dump valve.

7. In combination with an airplane, precise control distribution ofairplane fuel stores comprising a center fuel supply cell located innon-critical position with respect to the center of gravity of theairplane center of gravity and supplying cells in more critical C.G.posi tions at opposite sides of said supply cell, a manifold connectingsaid side cells, a transfer pump connected at inlet side with saidmanifold and at discharge side with said center cell, sequencing valvesin said manifold at opposite sides of said pump inlet, a timer connectedto alternately open said sequencing valves and to hold said transferpump energized for predetermined intervals of time whereby to feed saidcenter cell with predetermined quantities of fuel taken alternately fromthe respective side cells, a float actuated switch at said center cellconnected to start said timer and transfer pump when fuel in the centercell falls below a predetermined level and to stop said timer andtransfer pump when fuel taken from said side cells restores fuel in saidcenter supply cell to the original predetermined level and a pressureswitch located in the intake to the transfer pump and connected to turnoff said transfer pump and timer in event of malfunctioning of saidsequencing valves.

8. Liquid stores distribution system for holding the center of gravitytravel within prescribed limits comprising the combination of anon-critical center of gravity located supply cell from which liquid istaken and critical center of gravity located feed cells for replenishingliquid taken from the supply cell, a pump of limited capacity forremoving liquid as needed from the supply cell, a pump of greatercapacity for transferring liquid from the feed cells to the supply cell,liquid transfer connections between said feed cells, includingsequencing valve means operable to alternate withdrawal from differentfeed cells, said larger capacity transfer pump being connected at theinlet side with said transfer connections and connected at the dischargeside with said supply tank, a timer connected and arranged to time theaction of said transfer pump and liquid level control means in saidsupply cell connected to start and stop said timer in accordance withthe level of liquid in the supply cell.

9. Aircraft liquid stores distribution system comprising a center celland end cells at opposite sides of the same, a supply pump fordelivering liquid from the center cell, a transfer pump connected todeliver liquid from the end cells to said center cell, end cellselecting valves, a timer connected to control said selecting valves andvolume controlled means at said center cell connected to start saidtransfer pump and timer when liquid in the center cell is reduced to apredetermined value and to stop said transfer pump and timer when liquidin the center cell is restored to a predetermined value.

10. Aircraft liquid stores distribution system comprising a center celland end cells at opposite sides of the same, a supply pump arranged todeliver liquid from the center cell, liquid displacement means ofgreater capacity than said supply pump connected to deliver liquid fromthe end cells to said center cell, normally closed end cell selectingvalves, a timer connected to alternately open said selecting valves andvolume controlled means at said center cell connected to start saidliquid displacement means and timer when liquid in the center cell isreduced to a predetermined value and to "7 4 s. stop said liquiddisplacement means and timer when 2,363,622 Rice Nov. 28, 1944 liquid'inthe center cell is restored to predetermined 2,394,431 Curtis et al.Feb. 5, 1946 value. 2,557,438 Jo hnsgn June 19, 1951 2,759,424 DefibaughAug. 21, 1956 References Cited 1n the file of thls patent 5 FOREIGNPATENTS UNITED STATES PATENT-S 681,361 Great Britain Oct. zz, 19522,180,035 Cleghorn Nov. 14, 1939 719,012 Great Britain Nov. 24, 1952

